1. Field of the Invention
The present invention relates, in general, to a novel electric wiring system for use in vehicles.
2. Description of the Prior Art
Vehicles, in particular automobiles, have generally utilized conventional point to point wiring systems for both power and control functions. These systems have proven themselves to be reliable and adequate for many years. However, recently added demands have been placed on vehicular wiring systems due to the increased necessary for complex safety and emission control systems, and due to the public's increasing demand for vehicular amenities. These various demands have greatly increased the size and complexity of vehicular wiring systems.
Such large and complicated wiring systems are increasingly costly to produce due to the ever increasing cost of both labor and materials. Additionally, the reliability and serviceability of these systems have suffered due to the large increase in complexity. Also, the increased size of the wiring systems runs counter to the current trend toward reducing the size of vehicles due to the greatly increased cost of fuel. Thus if a vehicle's wiring system could be simplified, significant reductions in size and weight could be achieved thereby decreasing the fuel consumption of the vehicle. Significant savings in the cost of the vehicle would also occur.
Currently, several solutions to the problems existing with conventional wiring systems have been proposed. Generally these solutions have involved some form of Time Division Multiplexing utilizing digital technology.
FIG. 1 illustrates a typical prior art Time Division System known as a Ring-type system. In this system a central processing unit (CPU) 1 is connected to a power bus 3, a data bus 5, and a clock bus 7. Buses 3, 5, and 7 are continuous wire structures positioned in a generally circular path about the body of the vehicle. A fourth "ground" bus is provided by the body of the vehicle. The central processing unit 1 communicates with a plurality of terminal units 11a through 11d via the bus system. Each terminal unit, in turn, communicates with a plurality of peripheral units 13a through 13d via individual dedicated cables. The peripheral units are directly connected to the various switches, indicators, lights, motors, etc., used in the vehicle. Thus a switch command may be sent via one of the peripheral units 13a located in the vehicle's dashboard through the dashboard terminal unit 11a to the CPU 1 via the bus system and thenceforth onto a motor operated by one of the peripheral units 13c. An operational indicator signal may be sent from the particular peripheral unit 13c to an indicator peripheral unit in 13a by reversing the process. Two-way communication thus takes place under control of the CPU 1.
The prior art time division multiplexing systems, as illustrated in FIG. 1, do achieve a noticeable reduction in the quantity and complexity of the required system wiring; however, this improvement requires the use of numerous complex and costly hardware assemblies in the form of terminal units, peripheral units, and central processing units. These units are both costly to produce and to service in the field. Additionally, it should be noted that a significant quantity of wiring exists in a system in the form of the three buses.
The present invention provides a novel solution to these and numerous other problems existing in prior art vehicular wiring systems.